Field
Implementations of the present invention relate generally to components and systems for drilling. In particular, implementations of the present invention relate to drill rods having at least one of reduced overall weight, increased strength, or resistance to jamming and/or wedging.
Relevant Technology
Drilling core samples (or core sampling) allows observation of subterranean formations within the earth at various depths for many different purposes. For example, by drilling a core sample and testing the retrieved core, scientists can determine what materials, such as petroleum, precious metals, and other desirable materials, are present or are likely to be present at a desired depth. In some cases, core sampling can be used to give a geological timeline of materials and events. As such, core sampling may be used to determine the desirability of further exploration in a particular area.
In drilling relatively deep wells, such as those which reach a depth of several hundred to several thousand feet deep, a plurality of drill rod sections, which typically have conventional lengths, are coupled end-to-end together in series to form a drill string. The connection between these drill rod sections is made by fasteners, usually threaded fasteners. One limitation on the drilling of relatively deep wells is the drill string weight, which of course becomes greater and greater as the well depth is increased. Historically, drill rod sections have been made of steel with a substantially constant internal diameter; but with the deeper wells now being drilled, the heavier drill strings can impose fatiguing loads on the component drill rod sections and on the equipment used to rotate and raise and lower the drill string.
In order to properly explore an area or even a single site, many core samples may be needed at varying depths. In some cases, core samples may be retrieved from thousands of feet below ground level. In such cases, retrieving a core sample may require the time consuming and costly process of removing the entire drill string (or tripping the drill string out) from the borehole. In other cases, a faster wireline core drilling system may include a core retrieval assembly that travels (or trips in and out of) the drill string by using a wireline cable and hoist.
In operation, the time to trip the core sample tube in and out of the drill string often remains a time-consuming portion of the drilling process. The slow tripping rate of the core retrieval assembly of some conventional wireline systems in a drill string formed from conventional drill rod may be caused by several factors. For example, the core retrieval assembly of some wireline systems may include a spring-loaded latching mechanism. Often the latches of such a mechanism may drag against the interior surface of the drill string and, thereby, slow the tripping of the core sample tube in the drill string. Additionally, because drilling fluid and/or ground fluid may be present inside the drill string, the movement of many conventional core retrieval assemblies within the drill string may create a hydraulic pressure that limits the rate at which the core sample tube may be tripped in and out of the borehole. The increased internal diameter of the drill rod of the present invention helps to reduce the impact of these factors and provides an increased efficiency in operation.
Accordingly, a need exists for improved drill rods that address one or more of the issues described above. For example, there is a need for drill rods that have reduced overall weight while maintaining or minimizing loss of stiffness in bending and twisting and loss of support against the bending and twisting of a drill string passing therethrough, as well as using available material effectively to increase drilling load capacity.